Silver halide emulsions stabilized with nitroso derivatives of phenols

ABSTRACT

THE STABILIZATION OF A PHOTOGRAPHIC SILVER HALIDE EMULSION WITH A COMPOUND OF THE GENERAL FORMULA   1-(X=),4-(Y=),R&#39;&#39;-CYCLOHEXA-2,5-DIENE   WHEREIN X=O, N-OR, Y=N-OR, R=H, ALKYL GROUP WITH 1-4 CARBON ATOMS, ACYL, R&#39;&#39;=H, HALOGEN, ALKYL GROUP WITH 1-4 CARBON ATOMS.

United States Patent 3 725 077 SILVER HAHDE EMElLSfONS STABILIZED WITH NETROSO DERIVATIVES 0F PHENOLS Karl Kuffner, Unterhaclling, and Ernst Proeschel, Munich,

Germany, assignors to Agfa-Gevaert Aittiengesellschaft,

U.S. Cl. 96-409 4 Claims ABSTRACT OF THE DISCLOSURE The stabilization of a photographic silver halide emulsion with a compound of the general formula wherein X==O, NOR; Y=N-OR;

R=H, alkyl group with 1-4 carbon atoms, acyl; R=H, halogen, alkyl group with l-4 carbon atoms.

BACKGROUND OF THE INVENTION The present invention relates to a process for the stabilizing of photographic silver halide emulsions.

It is known that the silver halide of photographic layers may also be developed without exposure; this den sity is generally called a fog. For example, fog can thus result in photographic materials by excessively long storage, by storage at excessively high temperatures and moistures; furthermore, fog may result due to high pressure, this is termed pressure fog. Also chemical effects such as impurities of polyester material, precipitates from interleaving paper, the synthetic polymers, for example, polyvinylidene chloride polymer, used for the intermediate layer and adhesive layer, especially with respect to a polyester base, and atmospheric impurities often bring about fog. This disturbing fog is often accompanied by other factors which disadvantageously influence the quality of the photographic layer. These disadvantages include contrast and sensitivity instabilities, usually one contrast measure and one sensitivity measure loss because of the fog formation proceeding.

Previously, a great number of stabilizers of the most varied chemical nature have become known. There may be mentioned for example, the large group of mercapto compounds, of inorganic and organic mercury and gold compounds, of the triazaindolizine, and the use of hydroquinone derivatives. When in this connection also very good stabilizers are concerned, they nevertheless also exhibit deficiencies in their effectiveness, and it is often difiicult to find the correct or effective stability for a given emulsion.

It is an object of this invention to provide a stabilizer which helps prevention or limitation to a minimum of the above-mentioned disturbances, such as fog, contrast and sensitivity instabilities, in order that the sensitometric data of the initial condition of the emulsion layer, i.e. the fresh layer, may be maintained.

Another object is providing a stabilization method which assures fog-free storage specimens and eliminates disadvantages of the previously known stabilization methods or surpasses their effectiveness.

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SUMMARY OF THE INVENTION Compounds of the following general formula X=O, N-0R;

R=H, alkyl group with 1-4 carbon atoms, acyl; R=H, halogen, alkyl group with 1-4 carbon atoms are employed for stabilization of silver halide emulsions with the simultaneous obtainment of maximum sensitivity and density. Further, the elfect of the new stabilizers is not limited only to the casting of the emulsion on a triacetate base but instead stands out even more prominently with respect to casting the emulsion on a usually more extensively fogging polyester base.

DESCRIPTION OF THE PREFERRED EMBODIMENT According to the preferred embodiment of this invention the following compounds are useful in silver halide emulsions.

(1) Nitrosophenol or quinone monoxime, prepared according to Bridge A 277, p. 85.

(2) Quinone dioxime prepared according Nietzki, Kehrmann, B. 20, p. 614.

(3) 3-chloro-4-nitrosophenol or 3-chloro-4-monoxime quinone may be prepared as follows: 10 g. NaOH (1 mol +5 excess) are dissolved while stirring in 500 ml. H O; 25.7 g. m-chlorophenol (1 mol) and 13.8 g. NaNO (1 mol) are added one after the other while stirring. Cooled to 2 C. with a sodium chloride-ice mixture. Slowly added in drops 20 g. (10.8 ml.) concentrated H (1 mol) thinned with ml. H O. Restirred for 1 hour; allowed to stand overnight. The separated oil taken up in benzene; drawn off from the undissolved. The substance obtained from the benzene solution is already pure. F. C. (decomposition).

(4) Quinone monoxime methyl ether prepared according to Bridge, Liebigs Annalen der Chemie, hereinafter referred to as A., 277, p. 86.

(5) Benzoquinone (1,4) monoxime-ethylether prepared according to Bridge A 277, p. 92.

(6) Benzoquinone (1,4) monoxime-benzylether prepared according to Bridge, A 277, p. 94.

(7) Benzoquinone (1,4) monoxime-acetate prepared according to Bridge, A 277, p. 92.

(8) Benzoquinone (1,4) monoxime-carbonic acid methylester prepared according to Bridge A 277, p. 83.

(9) Benzoquinone-(1,4)-monoxime-carbonic acid ethyl ester prepared according to Walker, Berichte der Deutschen Chemischen Gesellschaft, hereinafter referred to as B., 17, p. 400.

(10) Z-chlorobenzoquinone (1,4) oxime(4)methylether prepared according to Bridge A. 277, p. 90.

(ll) 2-chloro-benzoquinone (1,4) oxime(4)acetate prepared according to Kehrmann, Grab A 303, p. 5.

(12) 2,S-dichlorobenzoquinone-(1,4)-monoxime prepared according to Kehrmann, Grab A 303, p. 13.

(13) 2,6-dichlorobenzoquinone-(1,4)-oxime prepared according to Kehrmann B 21, p. 3318.

14) 2-bromobenzoquinone-(1,4)-oxime-(4) prepared according to Kehrrnann B 21, p. 3317.

(15) 2-methylbenzoquinone 1(l,4) oxime-(4) prepared according to Bridge, Morgan Am. 20, S. 766.

(16) 2-methylbenzoquinone-(l,4)-oxime-(1) prepared according to Bridge, Morgan Am. 20, S. 766.

wherein (17) 2,6-dimethylbenzoquinone-( 1,4)-oxime- 1) prepared according to O. Fischer, v. Cammerloher, B 34, p. 948.

(18) 3-bromo 2,6 dimethylbenzoquinone (1,4)- oxime-(4) prepared according to Auwers, Markovits, B 41, p. 2338.

(19) 2,5-di-tert.-butylbenzoquinone-(1,4) monoxime prepared according to Bodtker, Bull. Soc. Chim. France (3) 3l,p. 970.

(20) 2,6-diethylbenzoquinone-(l,4)-oxime (1) prepared according to Karrer, Schlapfer, Helv. 24 (1941), p. 298.

(21) Tetramethylbenzoquinone-(1,4)-oxime-(4) prepared according to Summerford, Dalton, Am. Soc. 66 (1944), p. 1330.

These novel compounds may also be added to a layer adjacent to the emulsion layer; these compounds may equally be added separately in the substratum, foundation or superstratum and protective layer, respectively. In this connection, it is immaterial whether the silver halide layers are spectrally sensitized or treated With a chemical sensitizer known from patents or literature. Needless to say, these novel compounds may be combined also with the stabilizers known from literature and patents, such as triazaindolizine, mercapto compounds, Hg and Au compounds, etc. In this connection, it has been shown that the use of the novel compounds together with 1,3,4-triazandolizine, as descrbied by the fundamental article of Birr, Z. wiss. Phot. 1952, p. 2-27, is particularly effective with reference to the contrast stabilization. In addition, color components and other well known additives for photographic silver halide emulsions are employed according to the invention together with the antifogging agents.

The concentrations employed in the sense of the invention are generally l300 mg. per 100 g. AgNO The invention is explained in more detail by way of example:

EXAMPLE 1 A silver chlorobromide emulsion with approximately 20% mol bromide freed of the excess salts by coagulation procedure, which normally is used for line and halftone reproduction purposes, is digested in the presence of a stabilizer up to the sensitivity and contrast maxima. The emulsion is divided into three parts, the one part remains without additive, the second part is mixed with 200 mg. 7-hydroxy-5-methyl-1,3,4-triazaindolizine per 100 g. AgNO the third part is mixed with 40 mg. nitrosophenol per 100 AgNO Beside the uniform amounts of wetting agent, all three parts contain the same amount of gelatin hardening agent and softening agent. These assays are then cast onto a film base consisting of triacetate and polyester, dried, out into sensitometric strips. the one half stored for 72 hours at 60 C., the other part remaining without this thermal aftertreatment. The sensitometric strips are then exposed behind a stepped photometric absorption wedge and jointly developed for 3 minutes in a strongly alkaline p-methylaminophenol hydroquinone developer of the following composition: 1,000 ml. H 0, 2 g. p-methylaminophenol sulfate, 50 g. Na SO sic., 120 g. hydroquinone, 5 g. potassium bromide.

The result is as follows:

Fresh Fog After storage Sens. Fog Sens.

(a) In casting over acetate base:

Working with the same requirements and maintaining the method of operation. described in Example 1, 50 mg.

quinone dioxime are added to the emulsion in place of nitrosophenol.

The result is as follows:

Fresh After storage Fog Sens Fog Sens (a) In casting over acetate base:

Assay without additive 0. 04 19. 4 0. 10 20. 1 Assay with triazaindolizine. 0. 04 20. 2 0.09 21.0 Assay with quinone dioxime 0. 05 19. 2 0.05 20.0

(b) In casting over polyester has Assay without additive..- O. 04 20. 4 0. 40 21. 2 Assay with triazaindoliz-inez. 0.06 20.6 1. 10 20. 8 Assay with quinone dioxime 0. 04 20.0 0.06 20.0

EXAMPLE 3 Working with the same requirements and maintaining the method of operation described in Examples 1 and 2, mg. 3-chloro-4-nitrosophenol and 200 mg. triazaindolizine are added to the emulsion.

The result is as follows:

Fresh After storage Contr.

Fog Sens. Contr. Fog Sens.

(a) In casting over acetate base:

Assay without additive Assay with triazaindolizine. Assay with chloronitroso phenol Assay with chloronitrosphenol plus triazaindolizine (bi In casting over polyester base:

Assay without additive Assay with triazaindolizine. Assay with chloronitrosophenol. Assay with chloronitrosophenol plus tn'azaindolizine EXAMPLE 4 Working the same requirements and maintaining the method of operation described under 1 to 3, mg. monoximemethyletherquinone are added to the emulsion.

The result is as follows:

What is claimed is:

1. A light-sensitive photographic element having on a support at least one silver halide emulsion layer which contains in a stabilizing amount of 0.01 to 0.3 grams per 100 grams of silver nitrate, a stabilizer having the following formula:

R=H, alkyl group with 1-4 carbon atoms, acyl; R'=H, halogen, alkyl group with 1-4 carbon atoms.

2. The photographic element as claimed in claim 3 wherein the emulsion contains a stabilizing amount of triazaindolizine.

3. The photographic element of claim 1, wherein the support consists of a polyester.

4. The photographic element of claim 3, wherein the polyester is polyethylene terephthalate.

References Cited UNITED STATES PATENTS 3,396,022 8/1968 Dersch et a1. 96109 X 3,420,667 1/1969 Copeland 96-109 X J. TRAVIS BROWN, Primary Examiner W. H. LOUIE, JR., Assistant Examiner 

